On a recent trip the Los Angeles area, I stumbled upon a P-25 trunking control channel on 411.4500 MHz. I was located just south of the LAX airport in the Manhattan Beach area.
Using PRO96COM, I discovered that this trunked system was showing three frequencies, 411.4500, 412.4500 and 413.4500 MHz. The system showed a System ID of 001, Site 101 and WACN of 00001. The site status showed that it was in site trunking, and not networked to any other sites.
All of these seem to point to a site or system that was under test. While I monitored this control channel, there were no radio affiliations or other activity.
I have not seen activity on these frequencies in my past visits, but hopefully some of the folks living in the area can keep an ear on this and see what develops.